1. Field of the Invention
The present invention relates to a self-contained air conditioning unit. More particularly, the present invention concerns a discharge door assembly for use with a room air conditioning unit.
2. Description of the Prior Art
A room air conditioning unit typically adapted to be mounted in a window or through a wall to provide conditioned air to one or more rooms utilizes a conventional vapor compression refrigeration circuit. A compressor is utilized to increase the temperature and pressure of a refrigerant which is then condensed rejecting heat to ambient air. The condensed refrigerant then undergoes a pressure drop through an expansion device and is connected to an evaporator where it changes state from a liquid to a gas absorbing heat from the air to be conditioned. This gas is recycled to the compressor to complete the cycle. An evaporator fan is utilized to draw air to be conditioned through the evaporator heat exchanger such that heat may be rejected from the air to the refrigerant flowing through the heat exchanger. This conditioned air is then discharged into the enclosure. Apparatus is often provided to direct the flow of this discharged air into the desired location within the enclosure. Residential air conditioning units, especially those which extend through the wall of a residence or are mounted in a window of a residence, include a discharge port for discharging conditioned air from the unit into the space to be conditioned, and a door for controlling the opening of the port. When such a unit is not in use, the discharge door is normally closed for the purposes of appearance, to prevent persons from accidentally striking the door, and to prevent the insertion of articles into the discharge port. It is very important that the discharge door be open whenever the unit is operating, because failure to open the door can result in the build-up of ice on the evaporator coils of the unit which could seriously damage the unit. Moreover, such failure to open the door can cause the thermostatic controls of the unit to shut the unit down before the space has been conditioned.
Prior art devices have attempted to provide frictional devices for securing the discharge door in various positions such as by providing frictional engagement between a strap attached to a door and a plate. Additionally, prior art devices have attempted to provide coaxial end fittings on the door such that it can be rotated partially by the force of the discharged air and further opened by an application of manual force thereto. This was accomplished utilizing hinge pins having cylindrical body portions which frictionally engage the door and noncylindrical end portions which are mounted for limited rotation in a housing. The discharge door would rotate with the hinge pins a limited extent before the housing was contacted and thereafter the hinge pins would rotate around the housing. Another prior art device has combined a pin extending from the door into a slot and a pin extending from the casing into a groove in the door.
The present invention concerns a casing defining a discharge door opening and having multiple slots for the entry of air to be conditioned. A door for covering said opening is mounted such that two pins extending from each end of the door are inserted into the slots enabling a lost motion type rotation of the door to be achieved. The combination of pins and slots allows the door to be rotated about a constantly changing axis of rotation and furthermore provides for the bottom of the door to form a seal with the casing regardless of the door position.
Additionally, a friction wedge is provided having a friction surface which may secure the door in a position throughout a range of positions. The friction wedge additionally has an inclined surface which upon the door being partially opened contacts an edge of one of the slots. When the unit is operated, the conditioned air being discharged to the enclosure has sufficient pressure to force the door partially open until the inclined surface engages the slot. To further open the door a manual force is required since the frictional force exerted by the friction surface must be overcome.